1. Field of the Invention
The present invention relates to the field of laces for athletic shoes to enhance durability and comfort during the wearing of the shoes.
2. Statement of the Problem
Shoe laces are used to attach shoes to the feet of the individual wearing the shoes by conforming the upper portion of the shoe to the shape of the upper arch of the wearer and securing the shoe, typically by a knot, thereon. Normally, the wearer will tighten the lace so there is a pressure applied by the lace on the upper portion of the wearer's foot. However, the foot is at rest at the moment when the lace is tightened and tied. As the wearer begins to move, the foot inside the shoe undergoes a range of movement. These movements apply varying degrees of stress between the foot and the shoe. Most laces are either inelastic or have a limited range of elasticity. This combination of inelasticity of the lace and the stress between the foot and shoe creates pressure points on the foot and causes discomfort and possibly pain to the wearer. The foot is restricted from undergoing a natural range of motion by the increased tension from the lace. Even when the prior art laces would stretch, usually the range of elasticity would be exceeded so the lace is no longer resilient and the shoe becomes loose on the foot.
There have been a number of prior approaches to elastic laces. One approach utilized rubber shoe laces to alleviate the need to tie knots in the laces, as disclosed in U.S. Pat. No. 1,566,466 issued to Cleaver; U.S. Pat. No. 1,673,080 issued to Lamy; U.S. Pat. No. 1,667,276 issued to Weingarten; U.S. Pat. No. 1,740,506 issued to Grosser; U.S. Pat. No. 1,775,013 issued to Yugawa; U.S. Pat. No. 1,823,057 issued to Marx; and U.S. Pat. No. 2,004,702 issued to Luttman, Jr. These laces were formed from solid rubber which allowed some elasticity to allow the shoes to be slipped on and off without the necessity for retying or anchoring the ends of the laces. However, these laces had a relatively short life span due to the low abrasion resistance, limited elasticity, low tear strength and other factors. As the laces were stretched, the eyelets of the shoe and other parts of the shoe would cause abrasion of the laces leading to catastrophic failure of the lace. The rubber laces are also susceptible to environmental degradation, thus shortening the life span of the lace. Further, rubber laces are difficult to tie in knots, and once the knots are tied, even more difficult to untie.
Other approaches used a rubber inner lace with a fabric coating, but this decreased the elasticity of the lace, and was also susceptible to environmental degradation. Usually the inner elastic core breaks or loses enough elasticity to reduce its effectiveness.
One approach to overcome these problems is disclosed in U.S. Pat. No. 1,673,327, issued to Hahn. Hahn discloses using a series of short laces between opposing eyelets to decrease the abrasion and increase the life of the laces. However, this approach was only usable for a limited type of shoes, is relatively expensive and still has many of the above problems.
A modern approach to this problem is disclosed in U.S. Pat. No. 4,423,539 issued to Ivanhoe. Ivanhoe discloses a plastic lace having a plurality of spaced elastic strands covered by woven textile threads. This allows the lace to maintain its pressure even if one of the strands breaks. However, this lace still requires a textile covering to protect against abrasion and the environment.
A need still exists for a shoe lace that will provide uniform predetermined pressure through the lace regardless of the movement of the foot.
3. Solution to the Problem
The present invention solves these and other problems by providing a durable shoe lace that will enhance the comfort and performance of the wearer, particularly during athletic use.
The lace of the present invention is uniformly elastic to allow the shoe to conform to the foot of the wearer during periods of movement and non-movement.
The present invention further provides a shoe lace that is resistant to abrasion to increase the life of the lace.
The present invention provides a lace that is elastic, yet has a high tensile strength to withstand high stresses in the lace.
The present invention provides a lace that has a relatively high tear strength to resist shearing under stress.
The present invention provides a lace that is not susceptible to environmental degradation.
The present invention provides a lace that has a high level of toughness to withstand physical abuse.
These and other features will become evident from the following description of the invention taken in conjunction with the drawings.